aggs.asciidoc

Aggregations

Elasticsearch provides a full Java API to play with aggregations. See the {ref}/search-aggregations.html[Aggregations guide].

Use the factory for aggregation builders (AggregationBuilders) and add each aggregation you want to compute when querying and add it to your search request:

SearchResponse sr = node.client().prepareSearch()
        .setQuery( /* your query */ )
        .addAggregation( /* add an aggregation */ )
        .execute().actionGet();

Note that you can add more than one aggregation. See {ref}/search-search.html[Search Java API] for details.

To build aggregation requests, use AggregationBuilders helpers. Just import them in your class:

import org.elasticsearch.search.aggregations.AggregationBuilders;

Structuring aggregations

As explained in the {ref}/search-aggregations.html[Aggregations guide], you can define sub aggregations inside an aggregation.

An aggregation could be a metrics aggregation or a bucket aggregation.

For example, here is a 3 levels aggregation composed of:

• Terms aggregation (bucket)

• Date Histogram aggregation (bucket)

• Average aggregation (metric)

SearchResponse sr = node.client().prepareSearch()
    .addAggregation(
        AggregationBuilders.terms("by_country").field("country")
        .subAggregation(AggregationBuilders.dateHistogram("by_year")
            .field("dateOfBirth")
            .dateHistogramInterval(DateHistogramInterval.YEAR)
            .subAggregation(AggregationBuilders.avg("avg_children").field("children"))
        )
    )
    .execute().actionGet();

Metrics aggregations

aggregations/metrics.asciidoc

Bucket aggregations

aggregations/bucket.asciidoc